In a loom of the type where the weft is carried back and forth through the shed by a shuttle, the shuttle movement is brought about by the use of picker sticks. A swingable picker stick is located at each side of the loom and contacts the shuttle at the end of its motion to push the shuttle back in the opposite direction. The picker stick at each side of the loom swings in a vertical plane with angular deflection, which plane includes the loom lay and the path of the shuttle and the weft. In the past, the picker stick has been made of wood and often of laiminated wood whose layers are cemented together and impregnated with a substantial polymer. Wooden constructions has been desirable, first of all, because it is inexpensive and, secondly, because wood has inherent vibration damping from its very nature. While picker sticks of this type have operated in an adequate manner, nevertheless, it is desireable to increase the number of picks at which a given loom is operated, so that the loom is capable of higher production. When one attempts to speed up a loom with a wooden picker stick, however, the life of the picker stick (before it must be replaced), is somewhat limited. Therefore, even though wooden picker sticks are relatively inexpensive, the cost of replacing the stick overrides the desireable quality of cheapness; that is to say, in order to replace a broken or worn picker stick, it is necessary to shut down the machine. Of course, the overhead in the mill continues but without any production on that machine. Furthermore, it is necessary to supply skilled labor to repair the loom and replace the stick. It can be seen, then, that the economics of the weaving room can indicate possibly paying more money for a more substantial picker stick, if it is not only possible to operate the loom at a faster rate but also to avoid the downtime and repair costs.
Attempts in the past to make a longer-lasting picker stick, however, have been less than successful. For instance, attempts to use metals in the picker stick have always resulted in failure either because the metal is too heavy or, if a light alloy was used, had limited strength and life. A picker stick which is too heavy requires very large amounts of energy to overcome the inertia in its swinging motion and the light alloys are likely to be destroyed too quickly. Furthermore, most of the attempts to use materials other than wood in picker sticks have lead to vibration problems which arise because the picker stick is operated as a second degree lever with a normally free end, but which is struck a heavy blow at the time of contact with the shuttle. These and other difficulties experienced with the prior art have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a picker stick which is light in weight, which is practically indestructable, and which is not subject to vibration.
Another object of this invention is the provision of a picker stick which is light in weight and which, therefore, can be applied to existing looms and operated at a higher than normal speed without an increase in horsepower absorption by the loom.
A further object of the present invention is the provision of a picker stick which is reinforced in a novel manner by very strong fibers to resist destruction under heavy duty operation in a loom.
It is another object of the instant invention to provide a picker stick which is not subject to destructive vibration at high "pick" speeds.
A still further object of the invention is the provision of a picker stick which is simple in construction, which is inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance or attention.
It is a further object of the invention to provide a picker stick which is capable of an extremely long life of useful service, thus reducing downtime and labor costs in connection with the operation of a loom.
It is a still further object of the present invention to provide a picker stick having a very durable nature, but whose flexibility can be readily designed to have exactly the desired spring constant.
Another object of the invention is the provision of a picker stick designed in such a way that its resonant frequency can be selected to relate in a desireable way to the frequencies and harmonics present in the remainder of the loom.
Another object of the invention is the provision of a picker stick which can be operated at a high rate of speed without exceeding a permissable sound level.